Unicode support

[VortexCoyote]

Loading files with unicode currently crashes the editor. Investigate how we can support this format

[JaanJah]

I looked into this and found out that we probably have to load in another font and add a japanese/other glyph ranges to support more unicode characters.

Ref: https://github.com/ocornut/imgui/blob/master/docs/FONTS.md#font-loading-instructions

[UnnamedOrange]

It seems that the imgui open file dialog uses UTF-8 as its coding, though the type std::string or const char* is used. However, in Windows const char* means ANSI, which is not the same as UTF-8. An experiment is shown below. Change:

leraine-studio/source/modules/chart-parser-module.cpp

Line 99 in a362ac4

std::ifstream chartFile(InPath);

To:

	std::ifstream chartFile{std::filesystem::path(reinterpret_cast<const char8_t*>(InPath.c_str()))}; // Regard InPath as UTF-8.

(To support char8_t, use C++20.) This makes the constructor of ifstream work, while the former one will throw a "File not found!".

Note that there are more codes to be modified.

[UnnamedOrange]

Sample of InPath:

C:\Users\username\Desktop\测试\516517 DJ Sharpnel - Over the Fullereneshift

测试 in the path corrupts the routine, while a path in pure English will not.